Advanced eco-friendly and adsorptive membranes based on Sargassum dentifolium for heavy metals removal, recovery and reuse

Abstract

Promising adsorptive mixed matrix membranes consisted of cellulose acetate (CA), as a polymer, and fine grinded Sargassum dentifolium (S) with different ratios, as adsorbent micro-particles, were prepared and investigated for Cd2+ and Zn2+ metal-ions removal. Different analytical techniques as Attentuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray microanalysis (EDX), porosity and swelling were performed for the prepared membranes. The morphological investigation showed well dispersion of the algal micro-particles and the high pore density of the mixed membrane compared to the blank one (CA only). The effect of different parameters that affecting the adsorption process as Sargassum dentifolium embedding ratio, pH, contact time and metal ions concentrations were optimized in order to get the highest removal efficiencies followed by full factorial design experiment. The adsorption results showed the maximum removal efficiencies of the CA-S membrane for 100 mg L−1 of both Cd2+ and Zn2+ were 95.9 and 82.79 % with dose 1.5 g L−1 and 2 g L−1, respectively. The adsorption isotherm, kinetics, and regeneration studies were displayed in order to determine the nature of the reaction and re-usability of the membrane. The adsorption process was related to Freundlich isotherm that describes the multilayer and heterogeneous adsorption of molecules to the adsorbent surface, and the pseudo first order kinetic was the most represent kinetic model for the adsorption process. Factorial experiments displayed that, time, pH and interaction between time and pH were the most significant factors in the adsorption process. This study proposed a new generation of adsorptive mixed matrix membranes based on the cellulose acetate and the algal micro-particles.